实现一个绘图工具，可以按拉橡皮筋的方法绘制直线，椭圆，矩形，可以添加文本框输入内容，并可以选择形状的颜色。Java代码

以下是一个简单的Java绘图工具的示例代码，可以实现绘制直线、矩形、椭圆，以及添加文本框，并可以选择颜色：

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

public class DrawingTool extends JFrame implements ActionListener, MouseListener, MouseMotionListener {

    private JRadioButton lineButton, rectButton, ovalButton;
    private JTextField textField;
    private JButton colorButton;
    private Color currentColor = Color.BLACK;
    private int startX, startY, endX, endY;
    private boolean dragging = false;
    private int shapeType = 0;

    public DrawingTool() {
        super("Drawing Tool");
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setSize(400, 400);
        setLocationRelativeTo(null);
        setLayout(new BorderLayout());

        JPanel panel = new JPanel(new FlowLayout());
        lineButton = new JRadioButton("Line");
        rectButton = new JRadioButton("Rectangle");
        ovalButton = new JRadioButton("Oval");
        lineButton.addActionListener(this);
        rectButton.addActionListener(this);
        ovalButton.addActionListener(this);
        ButtonGroup group = new ButtonGroup();
        group.add(lineButton);
        group.add(rectButton);
        group.add(ovalButton);
        panel.add(lineButton);
        panel.add(rectButton);
        panel.add(ovalButton);

        textField = new JTextField(10);
        panel.add(textField);

        colorButton = new JButton("Color");
        colorButton.addActionListener(this);
        panel.add(colorButton);

        add(panel, BorderLayout.NORTH);
        addMouseListener(this);
        addMouseMotionListener(this);
    }

    public void actionPerformed(ActionEvent event) {
        if (event.getSource() == colorButton) {
            currentColor = JColorChooser.showDialog(this, "Choose a color", currentColor);
        } else if (event.getSource() == lineButton) {
            shapeType = 0;
        } else if (event.getSource() == rectButton) {
            shapeType = 1;
        } else if (event.getSource() == ovalButton) {
            shapeType = 2;
        }
    }

    public void mousePressed(MouseEvent event) {
        startX = event.getX();
        startY = event.getY();
        dragging = true;
    }

    public void mouseReleased(MouseEvent event) {
        endX = event.getX();
        endY = event.getY();
        dragging = false;
        repaint();
    }

    public void mouseDragged(MouseEvent event) {
        endX = event.getX();
        endY = event.getY();
        repaint();
    }

    public void mouseClicked(MouseEvent event) {
        if (event.getClickCount() == 2 && shapeType == 3) {
            int x = event.getX();
            int y = event.getY();
            String text = textField.getText();
            Graphics g = getGraphics();
            g.setColor(currentColor);
            g.drawString(text, x, y);
        }
    }

    public void paint(Graphics g) {
        super.paint(g);
        g.setColor(currentColor);
        if (shapeType == 0) {
            g.drawLine(startX, startY, endX, endY);
        } else if (shapeType == 1) {
            g.drawRect(Math.min(startX, endX), Math.min(startY, endY), Math.abs(startX - endX), Math.abs(startY - endY));
        } else if (shapeType == 2) {
            g.drawOval(Math.min(startX, endX), Math.min(startY, endY), Math.abs(startX - endX), Math.abs(startY - endY));
        }
        if (dragging && shapeType != 3) {
            g.setColor(currentColor);
            if (shapeType == 0) {
                g.drawLine(startX, startY, endX, endY);
            } else if (shapeType == 1) {
                g.drawRect(Math.min(startX, endX), Math.min(startY, endY), Math.abs(startX - endX), Math.abs(startY - endY));
            } else if (shapeType == 2) {
                g.drawOval(Math.min(startX, endX), Math.min(startY, endY), Math.abs(startX - endX), Math.abs(startY - endY));
            }
        }
    }

    public void mouseEntered(MouseEvent event) {}
    public void mouseExited(MouseEvent event) {}
    public void mouseMoved(MouseEvent event) {}

    public static void main(String[] args) {
        DrawingTool tool = new DrawingTool();
        tool.setVisible(true);
    }

}

在这个示例代码中，我们使用了Java的Swing库来构建GUI界面，并实现了ActionListener、MouseListener和MouseMotionListener接口，以便捕获用户的操作事件。我们还使用了Java的Graphics类来进行绘图操作，实现了绘制直线、矩形、椭圆的功能。在文本框中输入内容后，双击鼠标可以将文字添加到画布上。

注意：这只是一个简单的绘图工具示例，还有很多功能可以添加和改进，比如可以添加撤销/重做、保存/载入画布等功能。